A typical conventional field emission display is designated with reference numeral 10 in FIG. 1. The depicted field emission device 10 comprises a faceplate 11 and an opposing baseplate 12. In some conventional display configurations, faceplate 11 comprises a conductive member 13 having a phosphor coating 14 provided thereover and positioned to face baseplate 12. Member 13 is typically coupled with a positive electrode thereby forming an anode. Phosphor coating 14 is configured to emit light responsive to reception of electrons emitted from baseplate 12.
Baseplate 12 comprises a matrix addressable array of cathode emission structures or emitters 16 (only one emitter 16 is illustrated in FIG. 1). Emitter 16 is formed from a semiconductive substrate 17. A conductive gate 18 is provided spaced from substrate 17. An insulative layer 19 (i.e., silicon dioxide) is typically provided intermediate substrate 17 and conductive gate 18.
Responsive to the application of a voltage potential intermediate substrate 17 and conductor 18, electrons are emitted from emitter 16 towards faceplate 11. In particular, conductive gate 18 is provided at a voltage potential higher than the voltage of substrate 17. Such results in the emission of electrons from a tip of emitter 16. Simultaneously, the positive voltage bias applied to faceplate 11 attracts the emitted electrons toward phosphor coating 14. Light is generated responsive to electrons striking phosphor coating 14.
Unfortunately, it has been observed that a capacitive coupling 20 usually occurs intermediate gate conductor 18 and substrate 17 responsive to the application of a voltage potential therebetween. This resultant capacitance adversely affects the speed of operation of field emitter device 10. Such limits the usefulness of the depicted field emitter device configuration in particular applications, such as high frequency operations.
Therefore, a need exists to provide improved field emission devices which avoid the problems associated with the prior art devices.